IB Bio HL - Kim Spring Final 25 | Quizlet

Evolution

A change in heritable traits within a population, occurs via natural selection

Lamarckism

previous evolutionary (false), said evolution occurred via acquired traits during an organism's lifetime

Evolution

A change in heritable traits within a population, occurs via natural selection

Lamarckism

previous evolutionary (false), said evolution occurred via acquired traits during an organism's lifetime

Sequential Evidence

Evolutionary change visible in DNA/RNA/AA, fewer differences=more closely related

Sequence differences accounted by the splitting of ancestral species

Gene Family

Ex. Hox Gene, determines body plan during development, found in organisms w/ clear head-to-tale axis

Selective breeding

Artificial selection, deliberate breeding process to produce desired traits (starts with one species)

Purpose: increase frequency of desired traits in short period of time

Mimics and provides evidence of evolution

Diversity in domesticated animals & Plants (2)

in between breeds and from original wild species

Homologous Structures

Similar anatomical structures w/ different functions, inherited from common ancestors but adapted for different functions

ex. Pentadactyl limbs

Pentadactyl limbs

Similar bone arrangement of five-fingered limb shared in mammals, birds, amphibians, and reptiles

However each limb shows adaptation to their mode of locomotion

Analogous Structures

Different anatomical structures that have similar functions, result of convergent evolution

Inherited from different ancestor, but lived in similar habitats w/ similar selective pressures, thus similar adaptations

Speciation

Creation of new species from pre-existing species

Two separate species begin to evolve independently and can no longer interbreed when brought back together (biological species concept)

Reproductive Isolation

When barriers (not always physical) prevent gene flow between gene pools of two populations

ex. geographic separation (physical barriers)

Divergent/Differential Selection

Different selective pressures cause a population to become different over time

Differences:

-climate

-predation

-competition

Bonobos & Chimpanzees

Separated by Congo river, water level lowered at one point and chimps crossed to Bonobo side

Chimps then subject to same selective pressures as Bonobos and become absorbed into bonobos

Types of Speciation

Allopatric Speciation & Sympatric Speciation

Both require reproductive isolation:

Allopatric Speciation

Geographic barrier that creates physical isolation

Sympatric Speciation (3 types)

The formation of new species in populations that live in the same geographic area

-Behavioral isolation

-Temporal Isolation

-Mechanical isolation

Behavioral Isolation

two populations have different courtship rituals or mating rituals

Temporal Isolation

Two populations breed during different times of the year

Mechanical Isolation

Two populations are anatomically incompatible and cannot transfer sperm

Adaptations

Heritable traits that allow individuals to be better suited to their environments

Adaptive Radiation

Pattern of diversification where species from a common ancestor occupy different, vacant niches (ecological roles) to minimize competition and increase biodiversity

Darwin's Finches

Rapid evolution of single species, results in diversification as individuals with adaptations that match their unique selective pressures survive and reproduce

Seen in beak shape

Finches eventually occupy different niches

Interspecific Hybrids

result of cross-breeding different species, combines useful traits of both (hybrid vigor), but usually sterile

Barriers to hybridization

In evolutionary terms, energy spent on producing sterile offspring is a waste, thus, organisms use techniques like courtship rituals to prevent it

Polyploidy

Organism has more than 2 sets of homologous chromosomes, chromosome duplicate but fail to divide in meiosis

Autotetraploid

(4n), all chromosomes come from same organism, gametes were diploid

When fuse w/ haploid gamete, offspring are triploid (3n) and are sterile

Therefore autotetraploids = different species (biological species concept)

Hybrid

When two species cross breed, contains one set of chromosomes from each parent, chromosomes do not form homologous pairs and hybrid is sterile

Allotetraploid

(4n) - chromosomes are from different species

occurs when chromosomes duplicate but don't divide in meiosis

Can interbreed with other allotetraploids but not parents (therefore different species)

Smartweed

Example of alloploidy, two diploid gametes of two different species mated and formed tetraploid smartweed

Why is polyploidy more common in plants?

Self-pollination - plants possess both male and female parts (therefore don't need to worry about 1 male and 1 female polyploid plant for reproduction)

Asexual reproduction - Infertile polyploids can reproduce asexually

Advantages of Polyploid Crops

Produce seedless (infertile) fruits

Shows hybrid vigor by growing larger, showing better disease resistance

Asexual Reproduction (4)

1. involves one parent

2. uses mitosis

3. offspring are genetically identical to each other and to parent (no genetic variation)

4. adapted to stable environment

Asexual Reproduction Examples (3)

1. binary fission

2. budding

3. vegetative propagation

Asexual Reproduction Advantage

produces genetically identical offspring by individuals that are adapted to existing environment

also rapid reproduction (no need for mate), requires less energy

Sexual Reproduction (4)

1. involves two parents (male and female)

2. involves meiosis and fertilization

3. offspring are genetically unique from each other and parents (genetic variation)

4. may be better adapted to changing environment

Sexual Reproduction Examples (3)

internal fertilization, external fertilization, pollination

Sexual Reproduction Advantage

produces offspring with variation which increases adaptability to environmental changes

Meiosis

produces unique gametes by mixing parental genotypes, variation occurs via crossing over and independent assortment

Fertilization

combines gametes to produce original offspring different from parents

-it doubles chromosome number, requiring meiosis to halve it

-gametes are haploid, zygotes are diploid

Reproductive System

organ system responsible for creating offspring and passing on genetic information

-unlike other systems, structures differ by gender

Testis (pl. testes)

produces sperm and testosterone

Epididymis

stores sperm until it matures (gains mobility) and is ejaculated

Scrotum

skin fold that holds testes at a lower body temp (about 2 C colder)

-allows sperm to survive

Vas Deferens

muscular duct that propels sperm during ejaculation

Seminal Vesicle and Prostate Gland

secretes fluids with nutrients, prostaglandin, and anticoagulating enzymes to form semen

Prostaglandin

causes uterine contractions

Bulbourethral Gland

secretes alkaline fluid that neutralizes acidity in urine

Penis

enters vagina for semen ejaculation

Urethra

transfers semen and urine out of body via penis

Ovary

produces egg and oestradiol (type of estrogen)/progesterone

Fimbria (pl. fimbriae)

tissue that sweeps released oocyte (egg) into oviduct

Oviduct/Fallopian Tube

carries oocyte/embryo to uterus

-site of fertilization

Uterus

muscular organ where embryo develops

Endometrium

inner lining of uterus

-thickens in preparation of implantation of embryo and lost during menstruation

Cervix

neck of uterus

-protects fetus during pregnancy, dilates for childbirth

Vagina

birth canal

Vulva

outer area that protects internal reproductive organs

Puberty

biological transition from childhood to adulthood marked by secondary sexual characteristics and reproductive maturity

-regulated by hypothalamus-pituitary-gonadal (HPG) axis

Hypothalamus

secretes increasing amounts of gonadotropin-releasing hormone (GnRH) in childhood

-stimulates anterior pituitary (front) to release gonadotropins

like luteinizing hormone (LH) and follicle-stimulating hormone (FSH)

*part of puberty*

Female Sex Hormones

estrogen (oestradiol) and progesterone, both from ovaries

-causes development of secondary sex characteristics (body hair, breast development)

-regulates menstrual cycle

Male Sex Hormones

Testosterone (from testes)

-causes development of secondary sex characteristics (facial/body hair, muscle mass, deep voice)

-growth of testes/penis

-initiation of sperm production

Menstrual Cycle

produces an ovum (egg) which allows pregnancy

-begins at puberty, ends at menopause

-lasts about 28 days

Ovarian Cycle

The 28 days of the menstrual cycle as they apply to events in the ovary. The ovarian cycle has three subphases: the follicular phase, ovulation, and the luteal phase.

Follicular Phase (days 1-14)

Purpose: growth and maturation of follicles

-FSH stimulates follicle growth --> release oestradiol

-oestradiol release more FSH and begins LH (positive feedback, process repeats w/ more FSH—> more oestradiol)

*oestradiol inhibits FSH at higher levels (not yet)*

Follicles

clusters of cells surrounding a single egg

Ovulation (day 14)

Purpose: release oocyte from follicle

-LH causes surge in ovulation

-positive feedback w/ FSH/LH ends when follicle ruptures

*LH then inhibits FSH (negative feedback*

Luteal Phase (day 15-28)

Purpose: LH converts ruptured follicle to corpus luteum

-progesterone thickens and maintains endometrium

-with oestradiol, it inhibits both FSH and LH (negative feedback)

-decrease in FSH leads to decrease oestradiol (just making less, not gone)

oestradiol also supports uterine development

Corpus Luteum

helps produce progesterone

Uterine Cycle

The cycle that prepares the uterus for the growth of an embryo

3 Phases:

Menstrual Phase

Proliferative Phase

Secretory Phase

Menstrual Phase (day 1-5)

Purpose: drop in progesterone and estrogen sheds endometrium

-if fertilization does not occur, corpus luteum is converted to corpus albicans

No corpus luteum leads to decrease progesterone leads to increase FSH which begins cycle

Proliferative Phase (6-14)

Purpose: regrow endometrial lining

-if fertilization occurs, embryo releases hormones to sustain the corpus luteum

corpus luteum makes progesterone, which thickens/maintains endometrium for pregnancy

Secretory Phase (day 15-28)

Purpose: endometrium prepares for implantation

-increase blood supply and glandular secretions

-progesterone maintains uterine lining

Gametogenesis

process in which diploid cells become haploid gametes

-in males, sperm is produced via spermatogenesis

-in females, egg is produced via oogenesis

*both processes involve MITOSIS, MEIOSIS, and DIFFERENTIATION*

Spermatogenesis

production of spermatozoa (sperm)

location: seminiferous tubules of testes

Spermatogenesis Process (5)

CONTINUOUS

1. during puberty, spermatogonia (2n) continuously undergo mitosis

2. cells that divide from spermatogonia grow/mature into primary spermatocytes (2n)

3. after meiosis I, forms two secondary spermatocytes (n)

3. after meiosis II, forms four spermatids (n)

4. during differentiation, acquires a tail and becomes spermatozoa

5. detach from sertoli cells and move out of testes

Spermatogonia

2n

sperm stem cell, continuously divides but never differentiated (divides to produce primary spermatocytes)

Primary Spermatocytes

2n

produced by division of spermatogonia, undergo meiosis I

Secondary Spermatocytes

n

2 produced by meiosis I of primary spermatocytes, undergo meiosis II

Spermatids

n

4 produced by meiosis II of secondary spermatocytes, consists of the "head" of the sperm

Spermatozoa

produced by differentiation of spermatids, gets tail

Sertoli Cells

mother cells that provide nutrients for spermatids

Oogenesis

production of ova (egg)

location: ovaries

*DISCONTINUOUS*

Oogenesis Process Before Birth (2)

1. before birth, oogonia (2n) continuously undergoes mitosis

2. cells that divide from oogonia grow/mature into primary oocytes, enters prophase I (meiosis) and pauses until puberty

Oogenesis Process During Puberty (3)

1. during puberty, one primary oocyte completes meiosis I during each menstrual cycle

2. forms one larger secondary oocyte (n) which gets all the cytoplasm, and enters meiosis II & pauses until fertilization

also forms one smaller polar body that eventually degenerates due to unequal cytoplasmic division

Oogenesis Process During Ovulation

1. secondary oocyte is released from follicle and enters oviduct (fallopian tubes)

2. if fertilized, meiosis II is completed

3. forms ovum and another polar body via unequal division of cytoplasm

*if not fertilized, secondary oocyte is just removed from body w/ rest of period*

Oogonia

stem cell that produces primary oocytes in mitosis, female version of spermatogonia

Primary Oocyte

produced by division of oogonia, enters prophase I before birth and pauses until puberty

Secondary Oocyte

formed when meiosis I is completed during each menstrual cycle, enters meiosis II and pauses until fertilization

Ovum

fertilized egg, formed if secondary oocyte is fertilized and completes meiosis II after ovulation

Male/Female Gamete Production

Male: millions of sperm (small, motile)

-produced in testes via spermatogenesis

-released continuously

Female: limited number of ova (large, sessile)

-produced in ovaries via oogenesis

-released cyclically

Male Gamete Structure/Adaptations (4)

1. sperm streamlined for motility

2. head - haploid nucleus

3. midpiece - large amounts of mitochondria to fuel movement via atp

4. tail - flagellum for motility, made of microtubules

Sperm Head

contains acrosome, paired centrioles, and has minimal cytoplasm

Acrosome

has enzymes to degrade jelly coat of egg

Paired Centrioles

needed by zygote to begin mitosis

Female Gamete Structure/Adaptations (4)

1. egg contains large amount of cytoplasm w/ nutrients

2. zona pellucida

3. corona radiata

4. cortical granules

Zona Pellucida

protective jelly coat

Corona Radiata

follicular layer that provides structural support

Cortical Granules

released during fertilization to prevent polyspermy

Male vs. Female Hormone Regulation

Male: testosterone regulates spermatogenesis and secondary sex characteristics (muscle, body hair)

Female: estrogen/progesterone regulate ovarian and menstrual cycles and secondary sexual characteristics (breast development)

Male vs. Female Reproductive Roles

Male: produce/deliver sperm for fertilization

Female: produce eggs, provide site for fertilization, support embryo development